Valve for fuel injection systems



Feb. 9, 1943. c. M. BOVARD 2,310,350

VALVE FOR FUEL INJECTION SYSTEMS Filed Sept- 30, 1959 2 Sheets-Sheet 1 INVNTOR. CHARLES/1450144 R0.

Feb. 9, 1943.

c.-M. BovARD VALVE FOR FUEL INJECTION YSTMS Filed sept. zo, 1939 2 sheets-Shea?.

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Fatented geb@ @9 E VALVE FOR FUEU INJECTIQN SYSTEMS Charles M. Bovard, Mount Vernon, Ohio, assigner to Cooper-Bessemer Corporation, Mount Vernon, Ohio, a corporation of Ohio Application September 3,0, 1939, Serial No. 297,249

6 Claims. (Cl. 277-42) This invention pertains to improvements in liquid fuel injection systems for injection type internal combustion engines, such as Diesel engines.

Systems of this character have heretofore been proposed, as described for example in U. S. Patent 1,617,567 to C. M. Blanchard, in which fuel under pressure is supplied to the iniector or spray nozzle of a cylinder, through a cam-actuated poppetvalve and thence through a pressure-actuated check valve, a by-pass relief valve opening at atmospheric pressure into the fuel sump, being provided between the ppppet and check valves and arranged to open upon closure of the poppet valve following each fuel injection. The object of the by-pass is to drain ou fuel retained in the poppet valve outlet passage following each injection, thereby to insure a sharp-cuto of fuel injection and good atomization.

'This by-pass relief valve takes the form of a cam-actuated floating plunger containing an axial relief passage which is closed during fuel injection by abutment of this plunger against the poppet valve stem. Following the injection, however, the plunger drops away from the valve stem upon depression of the cam lever, thus exposing the relief passage to the poppet valve outlet for draining ou fuel retained in the passage between the poppet and check valves following an injection.

The check valve is provided adjacent the poppet valve fer the purpose of preventing air which enters the poppet valve outlet through the by-pass, from also entering the passage extending to the spray nozzle. Otherwise, owing to the high pressure at which the spray nozzle is set to operate, air entering this passage would tend to be merely compressed in the passage during each injection causing some or all of the fuel fed past the poppet valve to drain off through the atmospheric relief valve following each injection, so that fuel fed past the poppet valve would either not be ejected from the spray nozzle at all or would be ejected in insumcient amount causing the engine to die or misiire. This e'ect is particularly noticeable on starting the engine.

One defect resulting from the prior construction above described, results fromfailure of the poppet valve to close tightly when grit lodges thereunder.

` Under these circumstances the resulting fuel leakage through the atmospheric by-pass relief valve may reach such proportions that the fuel pump can not maintain adequate pressure thus causing the engine to stall. .Another defect resides in the presence of the check valve provided for reasons above stated. The check valve has the disadvantage that it traps line pulsations, which at times become very high and often cause the spray nozzle to open one or more times after the normal injection period. This invariably causes the engine to smoke and operate at high fuel consumption. It is, therefore, desirable to devise a satisfactory way of operating Without the check valve.

The present invention provides a construction which eliminates the necessity for the check valve, and also provides a substitute for the poppet valve which overcomes the above-mentioned defects incident thereto. In accordance with one aspect of this invention, there is provided in place of the single-closure poppet valve previously employed, a valve assembly comprising a plurality of small and independently seating disc valves, preferably three in number, arranged seriatim in a valve passage between the fuel inlet and outlet thereof, these disc valves being separated by short spacer studs to transmit the lift from one disc to another, the construction and Aoperation of the assembly being in other respects generally similar to that of the previously used single-closure poppet valve. That is to say, the valves are siv multaneously unseated by a cam-actuated plunger engaging the disc adjacent the valve outlet, and n are thereafter simultaneously seated by a compression spring engaging the disc adjacent the valve inlet.

With the proposed construction, the presence of grit in the fuel suppiy would not prevent valve closure, owing to the practical impossibility of grit lodging under all the discs simultaneously.

This is further assured bythe progressively increasing lift imparted to the discs from top to bottom owing to the slight clearances provided between the discs and the interposed spacers. Thus grit of such size as could pass through the valve assembly at all, could lodge only under the uppermost disc and would wash through the lower discs owing to their greater clearances. The lower discs would, therefore, be closed tightly by the fuel pressure and hence prevent leakage.

The necessity for the check valve of the prior construction referred to, is eliminated by the interposition of a helical compression spring between the iioating plunger comprising the by-pass relief valve, and the cam-actuated push-rod which operates the valve assembly. This spring holds the atmospheric by-pass relief valve normally closed to a definite predetermined pressure,

which prevents reexpansion below this pressure,

' of air in the fuel line extending to the spray nozspray nozzle fuel line, so that on s'rting a few additional injections of fuel through the disc valve, will force sufficient fuel through the spray nozzle for starting. Also during operation, the fuel accumulating in the disc valve outlet passage Will, by periodically forcing its way out of the relief valve against the com-pression of this spring,

prevent any substantial amount of air from en' tering the fuel line to the spray nozzle. On the other hand, the by-pass action of the relief valve still remains effective to prevent abnormal ejection of fuel through the spray nozzle, inasmuch as the nozzle is set to operate at a much higher fuel pressure than that exerted by the relief valve spring. The by-pass relief valve is of course prevented from opening while the disc valves areun seated to provide fuel injection, because during this interval the spring referred to is compressed by the action of the push-rod against the floating plunger thereby to maintain the relief passage closed.

In the drawings:

Fig. 1 is a diagrammatic showing of a valve mechanism in accordance with the invention as employed in an internal combustion engine of the injection type, the valve housing being shown in section axially of the valve, and the engine cylinders, crankshaft, etc., being shown schematically,

Fig. 2 is a detailed view of the entire valve assembly as shown in axial section; while Fig. 3 is an enlarged fragmentary view showing only the disc valve portion of the assembly in axial section, and arranged to illustrate the action when a piece of grit lodges under the Upper disc.

Referring to the drawings wherein like elements are similarly designated, the valve assembly comprises a housing I, having a bore 2 therethrough, closed at its lower end by a dowel 3 the' upper face of which seats a disc valve 4, housed within a socket-like cavity 5 of a sleeve member 6, through the axial bore of which extends a. longitudinally fluted spacer 1, and the upper face of which seats ya second'disc valve 8 likewise housed in a socket-like cavity of a second sleeve member 9, through the axial bore of which extends a second spacer I0 like 8, and the upper face of which seats a third disc valve II. Engaging the upper disc valve I I, is a compression spring I2, retained in position under compression by a body plug I3, threaded into the upper bore of the valve housing I, and containing an axial cavity I4 housing the upper portion of the spring. Interposed between the body plug I3 and the sleeve member 9 and surrounding spring I2,l is a fuel injection valve vspacer' I5, separated from the body plug and sleeve member by packings I6 and I1, respectively.

Fuel is fed to the valve assembly under pressure from a fuel pump (not shown) through an orifice I8 in the valve housing I and thence into a passage I9 of the housing, the fuel flow through which may be controlled by a normally open isolating needle valve 20, adjustable by means of a nut 2l. Passage I9 communicates with a peripheral groove 22 on the outer surface of the valve spacer I5, and from this groove the fuel passes to the interior of the valve spacer through radial passages 23 therein.

As shown in the drawings, the disc valves are after, the fuel passes from the interior of the valve spacer, past the peripheral edges and under the disc valves and along the longitudinal flutes in the interposed spacers to the dowel 3. The dowel contains an axial bore as shown housing a floating plunger 24, the upper end of which normally abuts the disc valve 4 as shown, and the diameter of which'is reduced at its upper end, at which end the bore of the dowel is increased, to provide an annular outlet fuel passage 25 communicating with radial passages 26 terminating in an outer peripheral groove 21 in the dowel. Communicating with groove 21'is a passage 28 in the valve housing and extending to a corresponding passage 29 axially drilled in a fitting 30 threaded into the valve housing as l shown. From this fitting, a fuel line 3| extends to the injector or spray nozzle 32 of one of the engine cylinders 33. In this way and when the disc valves are unseated, fuel is fed under pressure from the inlet I8 in the valve housing, through the valve assembly, dowel passages and fuelline, to the spray nozzle 32, whence the fuel is injected into the cylinder. It will be understood of course that there is provided for each of the remaining engine cylinders, such as 34, a similar valve assembly for injecting fuel over a Asimilar fuel line, such as 35, through the spray nozzle 36 of such cylinder.

The floating plunger 24 comprises the by-pass relief valve, and for this purpose is provided with an axial passage 31 extending from its upper end to a lateral aperture 33 near its lower end, which, with the disc valves seated as shown in Fig. 2, drains into a passage 39 provided by the valve housing, cover plate 49 supporting the housing,

and cover 4I, which passage in turn drains at substantially atmospheric pressure into the oil sump. Passage 31 is normally maintained closed at its upper end by abutment of the plunger f against the disc valve 4.

The floating plunger 24 seats on a crosshead 42 threaded into the upper end of a push-rod 43 foradjustably positioning the plunger in relation to the push-rod, a lock-nut 44 being provided to lock the crosshead at an adjustment desired. The push-rod seats in a socket bearing 45 car ried by a cam lever 46, which is rocked about a shaft 41 by a cam button 48 riding on a. cam disc 49 journaled to shaft 59 and provided with a cam nose 5I for rocking the cam lever.

The push-rod is journaled through a sleeve 52 extending through the cover plate as shown. and for maintaining passage 31 of the floating plunger normally closed, sleeve 52 is provided above the cover plate with a shoulder 53, between which and a shoulder 54 on a collar 55 surrounding the upper end of the push-rod, is interposed a helical compression spring 56. By theaction of this spring, the upper end of the plunger 24 is caused resiliently to engage disc valve 4 with such force as to close the relief valve passage 31 so long as the pressure in the outlet passages 25, 26, 21, etc., of the valve assembly, is below a preselected pressure for which spring 56 is designed. On the other hand. should the pressure exceed this value, it will force plunger 24 away from disc valve 4 for the interval required to discharge fuel or air or both through opening 38 to the extent required to reduce the pressure in the valve outlet passages to the preselected value. To provide for the resilient displacement of plunger '24, the pushrod 43 is made of such length as to leave a space 51 between its lower end and its seat 45 on the Y cam lever when the disc valves are seated, as

in Fig. 2. In this connection, it will be understood of course that the upward pressure exerted on plunger 24 by spring 56 is insulcient ing spring 56 ineffective and preventing theplunger from` moving away from'disc valve d to open the relief passage.

For actuating the valve assembly, cam disc 4S is driven by the main crankshaft 58 of the engine, as for example by means of the bevel gears 59, the operation being as follows: As the cam disc is rotated in the manner stated, cam nose I passing under cam button 48 elevates the cam lever t6 until seat 45 engages push-rod 53.

Further elevation of the cam lever elevates the.

push-rod and with it the remaining valve assembly comprising the plunger 24, valve discs 5. 9, H and interposed spacers 1, I0. The valve discs being thus unseated, fuel is forced under pressure, as above explained, from aperture IB past' the valve assembly to the spray nozzle. As the cam button 48 rides past the cam nose 5I, the cam lever returns to the position shown in Fig. 2, -and the valve discs are seated by the restoring action of the valve spring i2 and the fuel pressure acting against the valve discs to seat them against leakage despite the slight clearances provided between the spacers and discs. Meantime, the pressure exerted by the fuel retained in the feed line 3l and the dowel passages 25, 26, 2l, will depress plunger 2t and discharge fuel through opening 38 until thev fuel pressure in these passages equals that determined by spring 56, whereupon the by-pass valve will close.

The force exerted on plunger 24 by spring 55 is such as to assure operation of the .by-pass relief valve at a substantially lower pressure than that at which the spray nozzle is set to operate,

so that fuel cannot be injected into the cylinders during intervals of non-injection. If for example, the spray nozzle is set to operate at about 3000 pounds per square inch, the by-pass relief valve would preferably be set to operate at about 500 pounds per square inch byyirtue of the spring loading applied by spring 56. On the other hand, this loading on the by-pass relief valve will prevent air in substantialamount from entering the spray nozzle fuel line, and will trap suicient fuel therein to assure easy starting and eincient operation. l

The presence of grit in the fuel does noty prevent effective operation of the valve assembly. As above stated, grit of suilicient size to pass under and lodge under .the upper disc would wash past the lower discs owing to their .increased lift resulting from the slight clearances between the discs and spacers; whereas lodgment of grit under the upper disc would only prevent seating of this disc as shown in Fig. 3 by particle et, the lower discs being closed by the fuel pressure.

A feature of the disc valves is that, being very short, there is no tendency for them to stick in their guides, as they are fitted loosely enough,

as shown in the drawings, to prevent binding either by the presence of grit in the fuel-or by tilting of the'discs. 'I'his is in contrast to'the prior poppet valve construction above described wherein a small particle of grit or-dirt wedging between the long stem of the valve and'its guide can cause the valve to hang open.

I claim:

1. In a liquid fuel injection system for internal combustion engines: a fuel inlet, a fuel outlet and a. valve passage therebetween, a plurality of independently seating disc valves and associated valve seats arranged seriatim in said passage, means` -for simultaneously seating and unseating said valves including interposed valve spacers, a pressure-actuated relief valve adjacent said outlet, and means maintaining said relief valve in resilient engagement with one of said disc valves when seated for permitting actuation thereof when said disc valves are seated, by pressure in said outlet exceeding a preselected value.

2. In -a liquid fuel injection system for internal combustion engines: a fuel inlet, a fuel outlet and a valve passage therebetween, a plurality of disc valves and associated valve seats arrangedseriatim in said passage, means including a camactuated plunger for simultaneously opening and closing said valves, said plunger normally engaging the disc valve adjacent said outlet and containing a pressure relief outlet passage which is closed by said engagement, and means including a spring resiliently maintaining said engagement when the valves are seated for automatically relieving pressure n said outlet exceeding a preselected value.

3. In a liquid fuel injection system .for internal combustion engines: a fuel inlet, a fuel outlet and a valve passage therebetween, a plurality of disc valves and associated valve seats arranged seriatim in said passage, means for simultaneously seating and unseating said valves, including interposed valve spacers and a, spring and a camactuated plunger engaging the valves adjacent said inlet and outlet respectively, said plunger containing a pressure relief outlet passage closed by said engagement, and means including a spring resiliently maintaining said engagement when the valves are seated for automatically reducing pressure in said outlet to a preselected value between fuel injections.

4. In a liquid fuel injection system for internal combustion engines: a valve passage having a fuel inlet and a fuel outlet, aplurality of dise valves and associated valve seats arranged seriatim in said valve passage, means for simultaneously seating and unseating said valves, in-V cluding spacers therebetween, and a spring and a cam-actuated plunger engaging the valve discs adjacent said inlet and outlet respectively,`said' plunger having a pressure relief outlet passage which is closed by said engagement, and means including a spring resiliently maintaining said engagement when the valves are seated for automatically maintaining the pressure in said outlet between fuel injections at a preselected pressure substantially below that required to eject fuel from said outlet.

5. In a liquid fuel injection system for internal combustion engines: a fuel inlet, a fuel outlet, and a valve passage therebetween, a valve and a valve seat disposed in said passage, means including a cam-actuated plunger for seating and unseating said valve, said plunger normally engaging said valve adjacent said outlet and containing a pressure relief outlet passage which is closed by said engagement, and means inclu a spring resilently maintaining said engagement when said valve is seated for automatically relieving pressure insaid outlet exceeding a preselected value.

6. In a liquid fuel injection system for internal combustion engines: a fuel inlet, a fuel outlet, and a valve passage therebetween, a plurality o! disc valves and associated valve seats arranged said outlet.

CHARLES M. BOVARD. 

